Toenail fungus causes the nails of the toes to become visibly distorted, brittle or thickened, according to Healthline. Sometimes there is also a distinct odor emitting from the infected nail.
More specific visible signs of a fungal infection in the toenail include scaling underneath the nail, white or yellowish streaks on the surface of the nail, crumbling or brittleness at the tip of the nail or in a corner, yellow spots near the cuticle, or the complete loss of a nail, reports Healthline. Although there are over-the-counter treatments available for mild cases of toenail fungus infection, they are not very effective in the cases of more serious infections. After diagnosis, a physician commonly prescribes an oral antifungal medication. Even with such treatments, in about half the cases, the fungal infection returns and requires additional treatment. Treatment is not a success until a nail free of infection grows in fully.
Because there are other infections that may cause similar conditions on the toenails, an individual who suspects a fungal infection should consult a physician to confirm the diagnosis, asserts Healthline. The physician takes a scraping of the nail and analyzes the specimen under a microscope or sends it out to a lab to make sure of the source of the infection.